Method of assembly of composite core sandwich edge joint

ABSTRACT

A method for assembling a composite wall assembly edge joint including laying up a first composite face sheet, laying up a first composite buildup pad having a first tapered section onto the first composite face sheet and positioning a composite flute core member, including a tapered first portion with a first inclined surface and a second inclined surface. First inclined surface is positioned onto the first tapered section of the first composite buildup pad and a second portion of the composite flute core member extends from the tapered first portion along first composite face sheet. The method also includes laying up a second composite buildup pad having a second tapered section with the second composite buildup pad spaced apart from the first composite buildup pad and having at least a portion of the second tapered section overlying the second inclined surface of the tapered first portion.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. Pat. No. 10,173,406,issued on Jan. 8, 2019. The entirety of the foregoing patent isincorporated by reference herein.

FIELD

This disclosure generally relates to a method to assemble an edge jointfor composite materials and more particularly a method to assemble anedge joint for composite sandwich shell edges.

BACKGROUND

Composite structures are being developed to replace aluminum componentsfor use with space launch vehicles. Replacement of aluminum componentswith lighter, lower cost, and less thermally conductive compositecomponents will enable larger payloads, reduced operating costs andlonger missions due to propellant boil-off reduction.

In the construction of the composite structures, composite fluted coresandwich shell wall assemblies were employed. These wall assemblies wereused, for example, in the construction of an external structural wallassembly of a rocket or in the construction of a cryogenic tankassembly. Sections of the wall assemblies were joined together withjoint edge structures so as to connect adjoining sections of thestructure being assembled. As higher line load demands are encounteredand needed than originally used in smaller rockets or structurespositioned higher in a stack, for example, an improved edge jointconstruction is needed for constructing the structural assembly withcomposite fluted core sandwich shell wall sections.

The lighter load shell edge joints originally developed requiredrelatively large openings between intermittently spaced shell edgereinforcements to allow extraction of tooling. As a result of therelatively large openings, that construction did not permit more closelyspaced fasteners that would be needed for a joint that needed to carry ahigher load capacity. The lighter load shell edge joint constructionalso forced load into the face sheets of the structure at the ends ofthe flutes which necessitated positioning a local doubler for carryinghigher loads for which the original joint was not designed.

An improved method to assemble a composite wall assembly edge joint thatwill provide improved load carrying capabilities such that more load canbe carried and distributed permitting additional and more closely spacedfasteners. This improved shell edge joint performance for increased loadcapacity needs to be accomplished with minimizing the increase invehicle weight.

SUMMARY

An example method includes a method for assembling a composite wallassembly edge joint which includes steps of laying up a first compositeface sheet, laying up a first composite buildup pad having a firsttapered section onto the first composite face sheet and positioning acomposite flute core member, which includes a tapered first portioncomprising a first inclined surface and a second inclined surface. Thefirst inclined surface of the composite flute core member is positionedonto the first tapered section of the first composite buildup pad and asecond portion of the composite flute core member extends from thetapered first portion along first composite face sheet. The methodfurther includes the step of laying up a second composite buildup padhaving a second tapered section wherein the second composite buildup padis positioned spaced apart from the first composite buildup pad havingat least a portion of the second tapered section of the second compositebuildup pad overlying the second inclined surface of the tapered firstportion of the composite flute core member.

Another example method includes a method for assembling a composite wallassembly edge joint, comprising steps of laying up a composite firstface sheet, laying up a composite first buildup pad having a firsttapered section onto the composite first face sheet and positioning acured composite flute core member which includes a tapered first portionincluding a first inclined surface and a second inclined surface. Thefirst inclined surface of the cured composite flute core member ispositioned onto the first tapered section of the for composite builduppad with an adhesive film positioned between the first inclined surfaceand first tapered section. A second portion of the composite flute coremember extends from the tapered first portion along first composite facesheet wherein an adhesive film is positioned between the second portionof the composite flute core member and the first composite face sheet.The method further includes the step of laying up a second compositebuildup pad having a second tapered section wherein the second compositebuildup pad is positioned spaced apart from the first composite builduppad having at least a portion of the second tapered section overlyingthe second inclined surface of the tapered first portion of thecomposite flute core member with an adhesive layer positioned betweenthe second tapered section and the second inclined surface of thetapered first portion of the composite flute core member.

The features, functions, and advantages that have been discussed can beachieved independently in various embodiments or may be combined in yetother embodiments further details of which can be seen with reference tothe following description and drawings.

BRIEF SUMMARY OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a rocket showing an edge jointlocation on wall of rocket;

FIG. 2 is a partial cut away perspective view of a cross section of therocket shown in FIG. 1 with a cryogenic propellant tank on board;

FIG. 3 is a an enlarged partial cut away view of the joint edge of acomposite wall assembly of that which is encircled and designated as 3in FIG. 2;

FIG. 4 is cross section view taken along line 4-4 in FIG. 3;

FIG. 5 is a perspective view of a composite flute core member of thecomposite wall assembly shown in FIG. 3;

FIG. 6 is an enlarged partially cut away view of tapered end of thecomposite flute core member in FIG. 5;

FIG. 7 is a cross section view of the joint edge of the composite wallassembly as seen along line 7-7 in FIG. 3;

FIG. 8 is a perspective view of cross section as taken along line 4-4 ofFIG. 3;

FIG. 8A is an enlarged view of that which is encircled as 8A in FIG. 8;

FIG. 9 is a flow chart for a method for assembling a composite wallassembly edge joint;

FIG. 10 is a flow chart for a second example of a method for assemblinga composite wall assembly edge joint;

FIG. 11 is a cross section view of the joint edge of the composite wallassembly as seen along line 7-7 in FIG. 3 wherein this joint edge isassembled in accordance with the second example of the method forassembling a composite wall assembly edge joint as set forth in FIG. 10;

FIG. 12 is the cross section as shown in FIG. 4 wherein the compositeflute core member is supported with a collapsible support during layupof an edge joint assembly for the second example of the method forassembling the composite wall assembly edge joint;

FIG. 13 is a cross section view showing the providing of support betweenspaced apart first and second composite buildup pads during assembly ofedge joint;

FIG. 14 is a flow chart for a third example of a method for assembling acomposite wall assembly edge joint; and

FIG. 15 is an enlarged view of that which is encircled as 8A in FIG. 8showing an edge joint assembled in accordance with the third example ofthe method for assembling a composite wall assembly edge joint as setforth in FIG. 14.

DESCRIPTION

As mentioned earlier, composite structures are being developed toreplace aluminum components or structures for use with a space launchvehicle or rocket 10, such as shown in FIGS. 1 and 2. Replacement ofaluminum components with lighter, lower cost, and less thermallyconductive composite components will enable larger payloads, reducedoperating costs and longer missions due to propellant boil-offreduction.

In the construction of the composite components or structures, anexample of such components or structures include using composite flutedcore sandwich shell wall assemblies. These wall assemblies are used, forexample, in the construction of different portions of rocket or launchvehicle 10 such as for an external structural wall assembly 12 of rocket10, or in another example for a cryogenic propellant tank with a skirtassembly 14, as seen in FIGS. 1 and 2, respectively. Other components ofvarious versions of rocket 10 can also be constructed with compositestructures such as, an inter stage section for a multiple stage rocketas well as for other portions of a rocket. As mentioned above, anexample of assembling a composite sandwich shell wall assembly 12 withan improved joint edge 16 will be discussed herein. Improved joint edge16 joins together, in this example, first section 18 to second section20 of wall assembly 12 and will provide improved performance for higherline load demands with minimizing weight increase in vehicle or rocket10.

In referring to FIG. 3, edge joint 16 is shown connecting first section18 to second section 20 of wall assembly 12. Composite fluted coresandwich shell wall assembly 12 includes first or inboard composite facesheet 22 and spaced apart second or outboard composite face sheet 24.Positioned within the spaced apart first and second composite facesheets 22 and 24 are a plurality of flute composite core members 26. Anexample of flute composite core member 26 is shown in FIGS. 5 and 6. Inthis example of wall assembly 12, flute composite core members 26 aretrapezoidal in shape, as seen in FIG. 4 however the shape can beselected from one of a number of shapes. In this example, trapezoidalshaped flute composite core members 26 are positioned between first andsecond composite face sheets 22, 24 in succession forming core assembly28, as seen in FIG. 4. Flute composite core members 26 can be furtherreinforced with employing a noodle 30 structure positioned in a cavity32 that forms between adjacent radiuses 31 and 33 of flute compositecore members 26 and first composite face sheet 22, as well as, betweenadjacent radiuses 35 and 37 of flute composite core members 26 andsecond composite face sheet 24. Wall assembly 12 with core assembly 28provides a strong and lightweight construction.

In referring to FIGS. 5-8A, composite fluted core sandwich wall assembly12 with edge joint 16 is shown which accommodates higher line loaddemands exerted through edge joint 16, whether exerted in compression orin tension. In referring to FIG. 7, first composite buildup pad 34having first tapered section 36 is secured to and extends along first orinboard composite face sheet 22. Second composite buildup pad 38 havinga second tapered section 40 is secured to and extends along second oroutboard composite face sheet 24. First and second composite builduppads 34 and 38 are positioned between spaced apart first and secondcomposite face sheets 22 and 24. Composite flute core member 26 includestapered first portion 42 and is positioned between and secured to firsttapered section 36 and to second tapered section 40. Second portion 44,as seen in FIG. 5, of composite flute core member 26 is positionedbetween, extends along and is secured to first and second composite facesheets 22 and 24. Second portion 44 of composite flute core member 26extends in direction 46 away from first portion 42. This construction oftapered first portion 42 of flute composite core member 26 being securedto first and second tapered sections 36 and 40 of first and secondcomposite buildup pads 34 and 38, respectively, provides enhanced loadline capabilities for joint edge 16.

As seen in FIGS. 7, 8 and 8A, first composite buildup pad 34 extends ina direction 48 away from first end 50 of first or inboard compositesheet face 22. First tapered section 36 of first composite buildup pad34 has first inclined surface 52 with a thickness T of first taperedsection 36 reducing in dimension as first composite buildup pad 34extends in direction 48 away from first end 50. Second composite builduppad 38 extends in direction 54 away from second end 56 of second oroutboard composite sheet face 24. Second tapered section 40 of secondcomposite buildup pad 38 has second inclined surface 64 with thicknessT′ of second tapered section 40 reducing in dimension as secondcomposite buildup pad 38 extends in direction 54 away from second end56.

First portion 42 of flute core member 26 has first inclined surface 58relative to first composite face sheet 22. Inclined surface 58 extendsalong first inclined surface 52 of first composite build up pad 34 suchthat first inclined surface 58 of first portion 42 of composite flutecore member 26 is positioned further from first composite face sheet 22as first portion 42 of composite flute core member 26 extends indirection 60 toward first end 50 of first composite face sheet 22. Firstportion 42 of composite flute core member 26 has second inclined surface62 relative to second or outboard face sheet 24 which extends alongsecond inclined surface 64 of the second build up pad 38 such thatsecond inclined surface 62 of first portion 42 of composite flute coremember 26 is positioned further from second or outboard face sheet 24 asfirst portion 42 extends in direction 66 toward second end 56 of secondcomposite face sheet 24.

As seen in FIGS. 5 and 6, first portion 42 of composite flute coremember 26 includes first wall member 68 with first inclined surface 58of first portion 42 of composite flute core member 26 positioned onfirst wall member 68. First portion 42 of composite flute core member 26includes second wall member 70 with second inclined surface 62 of firstportion 42 of composite flute core member 26 is positioned on secondwall member 70. First wall member 68 and second wall member 70 arespaced apart a as seen for example as distance D, as seen in FIG. 6, andconverge as first wall member 68 extends in direction 60 of first end 50of first composite face sheet 22, as seen in FIG. 7, and second wallmember 70 extends in direction 66 of second end 56 of the secondcomposite face sheet 24.

As seen in FIGS. 5-8A, first inclined surface 58 of first portion 42 ofcomposite flute core member 26 is co-cured to first inclined surface 52of first composite build up pad 34. Second inclined surface 62 of thefirst portion 42 of the composite flute core member 26 is co-bonded tothe second inclined surface 64 of second composite build up pad 38.Second portion 44 of composite flute core member 26 is co-bonded tofirst composite face sheet 22 and to second composite face sheet 24.First composite build up pad 34 is co-bonded to first composite facesheet 22 and second composite build up pad 38 is co-cured to secondcomposite face sheet 24.

In referring to FIGS. 7, 8 and 8A, bridge composite structure 72 ispositioned between first composite buildup pad 34 and second compositebuildup pad 38. Bridge composite structure 72 is secured to both firstand second build up pads 34 and 38 and extends along first compositebuildup pad 34 in direction 48 away from first end 50 of first compositeface sheet 22 and extends along second composite buildup pad 38 indirection 54 away from second end 56 of second composite face sheet 24.

Bridge composite structure 72, in this example, is post bonded to firstcomposite build up pad 34 and is post bonded to second composite buildup pad 38. Further included is first hole 74 which extends in firstdirection 76 through first composite sheet face 22, first compositebuild up pad 34, bridge composite structure 72, second composite builduppad 38 and second composite face sheet 24. First portion 78 of secondhole 80 extends through bridge composite structure 72 in seconddirection 82 transverse to first direction 76 of first hole 74 such thatfirst portion 78 of second hole 80 is in communication with first hole74 and second portion 84 of second hole 80 extends within bridgecomposite structure 72 in second direction 82 spaced apart across firsthole 74 and aligned with first portion 78 of second hole 80.

Further included is barrel nut 86 having hole 88, which extends throughbarrel nut 86, with barrel nut 86 positioned within first hole 74 ofbridge composite structure 72. Barrel nut 86 has threaded surface 90defined by inner wall surface 92 of hole 88 with hole 88 of barrel nut86 positioned aligned with first and second portions 78 and 84 of secondhole 80 of bridge composite structure 72. Bolt 94 includes threads 96compatible to threaded surface 90 defined by the inner wall surface 92of hole 88 of barrel nut 86. Bolt 94 is positioned within first portion78 of second hole 80 of bridge composite structure 72. Threads 96 ofbolt 94 engage threaded surface 90 defined by inner wall surface 92 ofhole 88 of barrel nut 86. With bolt 94 engaged and tightened, as seen inFIG. 7, first section 18 is secured to second section 20 of wallassembly 12.

As will be appreciated in the discussion of an example of the assemblyof edge joint 16, composite bridge structure 72 will be installed as alatter element in the joint edge 16 construction which includes thecomponents of first composite or inboard sheet face 22, first compositebuildup pad 34, flute composite core member 26, second composite builduppad 38 and second composite or outboard face sheet 24. With thesecomponents assembled composite bridge structure 72 is installed alongwall assembly 12. Composite bridge structure 72 can provide thefabricator as needed a substantially continuous wall which extends aboutwall assembly 12 in which to drill second holes 80 with intersectingcorresponding first holes 74. With a substantially continuous wallestablished by bridge composite structure 72, the fabricator has theflexibility of selectively spacing connecting assemblies of barrel nuts86 and bolts 94 along joint edge 16 of wall assembly 12 to accommodateload demands as needed through joint edge 16 along wall assembly 12 inconnecting, for example, section 18 to section 20 of wall assembly 12.As a result, the fabricator selects the spacing and employs the spacing,as can be seen for example in FIG. 3, as required for load transferenceacross joint edge 16. The load lines will extend along first and secondbuildup pads 34 and 38, along first and second tapered sections 36 and40, engage first and second walls 68 and 70 of composite flute coremember 26 and in turn extend into first and second face sheets 22 and 24providing joint edge 16 with an enhanced performance for wall assembly12.

In referring to FIG. 9, an example of method 100 for assemblingcomposite fluted core sandwich shell wall assembly 12 edge joint 16 isshown. Method 100 includes step 102 of laying up first composite builduppad 34 having a first tapered section 36 onto a cured first composite orinboard face sheet 22, with an adhesive layer 43, as seen in FIG. 8A,positioned between first composite buildup pad 34 and first compositeface sheet 22. Step 102 of laying up first buildup pad 34 furtherincludes the step of laying up of first buildup pad 34 which extends ina direction 48 away from first end 50 of first composite face sheet 22and configuring first tapered section 36 having first inclined surface52 with thickness T of first composite buildup pad 34 reducing indimension as first composite buildup pad 34 extends in direction 48 awayfrom first end 50.

Method 100 further includes step 104 of positioning composite flute coremember 26, which includes tapered first portion 42, having a firstinclined surface 58 and a second inclined surface 62, wherein, firstinclined surface 58 of composite flute core member 26 is positioned ontofirst tapered section 36 of first composite buildup pad 34. Secondportion 44 of composite flute core member 26, as seen in FIG. 5, extendsin direction 46 away from first portion 42 along first composite orinboard face sheet 22, as seen in FIGS. 7 and 8A, with adhesive film 43positioned between second portion 44 of flute composite core member 26and first composite face sheet 22. Step 104 of positioning of compositeflute core member 26 further includes positioning first inclined surface58 of composite flute core 26 overlying first inclined surface 52 offirst composite buildup pad 34 such that first inclined surface 58 ofcomposite flute core member 26 increases in distance away from firstcomposite face sheet 22 as composite flute core member 26 extends in adirection 60 toward first end 50 of first composite sheet face 22.

Method 100 further includes step 106 of heating at least first compositebuildup pad 34 and composite flute core member 26, co-curing firstcomposite buildup pad 34 and composite flute core member 26 and securingtogether first tapered section 36 of first composite buildup pad 34 withfirst inclined surface 58 of composite flute core member 26 andco-bonding second portion 44 of composite flute core member 26 to firstcomposite or inboard face sheet 22. At the same time, first compositebuild up pad 34 is co-bonded to first composite face sheet 22.

Method 100 further includes step 108 of laying up second compositebuildup pad 38 having a second tapered section wherein the secondcomposite buildup pad is positioned spaced apart from first compositebuildup pad 34 and with at least a portion of the second tapered sectionof second composite buildup pad 38 overlying an adhesive film 39, asseen in FIG. 8A, positioned overlying second inclined surface 62 offirst portion 42 of composite flute core member 26. Step 108 of layingup second composite buildup pad 38 includes configuring second inclinedsurface 64 of second composite buildup pad 38 with second compositebuildup pad 38 reducing in thickness T′ as second composite buildup pad38 extends in direction 54 away from second end 56 of second compositeface sheet 24 with second inclined surface 62 of first portion 42 ofcomposite flute core member 26 decreases in distance from firstcomposite face sheet 22 as second inclined surface 62 of composite flutecore member 26 extends in direction 60 toward first end 50 of firstcomposite face sheet 22.

With second composite buildup pad 38 positioned overlying secondinclined surface 62 of composite flute core member 26 step 110 isemployed of heating at least second composite buildup pad 38 andco-bonding second composite buildup pad 38 to second inclined surface 62of first portion 42 of composite flute core member 26.

Step 108 of laying up second composite buildup pad 38 further includesthe step of laying up a second composite face sheet 24 onto secondcomposite build-up pad 38 and onto second portion 44 of composite flutecore member 26 with positioning adhesive film 39 between second portion44 of composite flute core member 26 and second composite face sheet 24,as seen in FIG. 8A. Step 110 of heating at least second compositebuildup pad 38 further includes co-curing second composite buildup pad38 and second composite face sheet 24 together and co-bonding secondportion 44 of composite flute core member 26 to second composite facesheet 24.

Method 100 further includes a step of laying up composite bridgestructure 72 and post bonding composite bridge structure 72 to first andsecond composite buildup pads 36 and 38 respectively, with adhesive film41, as seen in FIG. 8A. Adhesive film 41 is positioned between compositebridge structure 72 and first composite build up pad 36 and betweencomposite bridge structure 72 and second composite buildup pad 38.

With composite bridging structure 72 post bonded to first and secondcomposite buildup pads 34 and 38, respectively, the step of laying upcomposite bridge structure 72 further includes a step of drilling firsthole 74 in a first direction 76 through first composite face sheet 22,first composite buildup pad 34, composite bridge structure 72, secondcomposite buildup pad 38 and second composite face sheet 24. The step oflaying up the composite bridge structure 72 further includes a step ofdrilling first portion 78 of second hole 80 in composite bridgestructure 72 in a direction 82 transverse to first direction 76 placingfirst portion 78 in communication with first hole 74 and continuedrilling second portion 84 of second hole 80 spaced apart across firsthole 74 from first portion 78 of second hole 80 and aligned with firstportion 78 of second hole 80. With first hole 74 and second hole 80drilled, the step of laying up composite bridge structure 72 furtherincludes a step of inserting barrel nut 86 into first hole 74 andinserting bolt 94 into second hole 80 and securing bolt 94 to barrel nut86. With securement of bolt 94, first section 18 and second section 20of wall assembly 12 are secured together as seen in FIG. 7.

A second example of a method for assembling a composite wall assembly 12edge joint 16 includes method 200, as set forth in FIG. 10. Thecomponents of the assembly of composite wall assembly 12 edge joint 16fabricated under method 200 that are common to previously describedcomponents for the assembling of composite wall assembly 12 edge joint16 fabricated under method 100 are similarly numbered. As will beappreciated herein, the assembly fabricated under the second example ofa method or method 200, in contrast to the assembly fabricated undermethod 100, the components of composite wall assembly 12 edge joint 16under method 200 are co-cured.

In referring to FIG. 10, method 200 for assembling a composite wallassembly 12 edge joint 16, includes step 202 of laying up firstcomposite face sheet 22, as seen in FIG. 11. In this example, firstcomposite face sheet 22 is an inboard face sheet of this assembly.Method 200 further includes step 204 of laying up a first compositebuildup pad 34 having a first tapered section 36 onto first compositeface sheet 22. Step 206 includes positioning composite flute core member26 which includes tapered first portion 42 with first inclined surface52 and second inclined surface 64. First inclined surface 58 ofcomposite flute core member 26 is positioned onto first tapered section36 of first composite buildup pad 34. Second portion 44 of compositeflute core member 26 extends from tapered first portion 42 along firstcomposite face sheet 22.

Method 200 further includes step 208 of laying up second compositebuildup pad 38 having second tapered section 40. Second compositebuildup pad 38 is positioned spaced apart from first composite builduppad 34 having at least a portion of second tapered section 40 of secondcomposite buildup pad 38 overlying second inclined surface 62 of taperedfirst portion 42 of composite flute core member 26.

Step 204 of laying up first buildup pad 34 further includes the step oflaying up of first buildup pad 34 to extend in a direction away fromfirst end 50 of first composite face sheet 22 with first tapered section36 having first inclined surface 52 with first tapered section having athickness T reducing in dimension as first composite buildup pad 34extends in direction 48 away from first end 50.

Step 206 of positioning of composite flute core member 26 furtherincludes positioning first inclined surface 58 of composite flute coremember 26 overlying first tapered section 36 having a first inclinedsurface 52 of first composite buildup pad 34, such that first inclinedsurface 58 of composite flute core member 26 increases in distance awayfrom first composite face sheet 22 as composite flute core member 26extends in direction 60 toward first end 50 of first composite sheetface 22.

Step 208 of laying up second composite buildup pad 38 having secondtapered section 40 including configuring second tapered section 40having a second inclined surface 64 with second tapered section reducingin thickness T′ as second composite buildup pad 38 extends in adirection 54 away from first end 50 of first composite face sheet 22.Second inclined surface 62 of tapered first portion 42 of compositeflute core member 26 is positioned closer to first composite face sheet22 as second inclined surface 62 of composite flute core member 26extends in direction 66 toward first end 50 of first composite facesheet 22.

Method 200 further includes a step of laying up second composite facesheet 24 onto second composite buildup pad 38 and onto second portion 44of composite flute core member 26. Second portion 44 of composite flutecore member 26 extends from tapered first portion 42 of composite flutecore member 26.

In fabricating composite joint edge assembly 16 under method 200, thecomposite material will be supported during the assembling of thecomposite material and co-curing of joint edge assembly 16. Thesupporting of the composite material will maintain the compositematerial in alignment and free from distortion that would otherwise beimparted to the composite material by the weight of the compositematerial prior to the composite material being cured. Support will beprovided within interior 61 of composite flute core member 26 and withinspacing 73 between first composite build up pad 34 and second compositebuild up pad 38, seen for example in FIG. 13.

In supporting composite flute core member 26, support is provided withininterior 61 on opposing surfaces 63 of tapered first portion 42,opposing surfaces 65 of second portion 44 of composite flute core member26 as well as opposing surfaces 79 on opposing side walls, as seen inFIG. 12. One example of supporting composite flute core member 26includes a step of inserting pressurized gas into interior 61 ofcomposite flute core member 26. Interior 61 is sealed off, not shown,and an access can be provided to interior 61 to adjust thepressurization within interior 61 as needed. The pressurized gas can bereleased from interior 61 of composite flute core member 26 when theco-curing process is completed. The pressurized gas can, as in thisexample, leave interior 61 of composite flute core member 26 and passthrough space 73, as seen in FIG. 13, between first composite build uppad 34 and second composite build up pad 38.

Another example of supporting of composite flute core member 26 includesa step of inserting a collapsible support structure 67, as schematicallyshown in FIG. 12, into interior 61 of composite flute core member 26.Collapsible support structure 26 can be inserted in a collapsed positionthrough space 73 positioned between first composite build up pad 34 andsecond composite build up pad 38 and through opening 69 of tapered firstportion 42 of composite flute core member 26. With collapsible supportstructure 67 positioned within interior 61 of composite flute coremember 26, collapsible support assembly 67 can be deployed such thatplates 75 are positioned and provide support against interior 61 surface65 positioned on opposing sides of composite flute core member 26 insecond portion 44 of composite flute core member 26 as seen in FIGS. 11and 12. Collapsible support assembly 67, in second portion 44 ofcomposite flute core member 26 also includes plates 77 positioned insupporting position against interior 61 surface 79 positioned onopposing sides of composite flute core member 26 as seen in FIG. 12.Other plates of collapsible support assembly 67 (not shown) arepositioned against interior surface 63 on opposing sides of taperedfirst portion 42 of composite flute core member 26 to provide support totapered first portion 42 during assembly and co-curing. At thecompletion of co-curing collapsible support assembly 67 is collapsed andreduced in profile. Collapsible support assembly 67 is removed orotherwise pulled from interior 61 of composite flute core member 26through opening 69 of composite flute core member 26 and then out ofedge joint 16 through space 73 between first composite build up pad 34and second composite build up pad 38. Removal of collapsible supportassembly 67 through space 73 is accomplished with any obstructions inspace 73 removed as needed. This is also the case with the removal ofcollapsible support from within tapered first portion 42 of compositeflute core member 26 as needed.

Similarly support is needed to be positioned between first compositebuild up pad 34 and second composite build up pad 38 during assemblingof edge joint 16 and during co-curing of edge joint 16. In referring toFIG. 13 a second support assembly 71 is positioned between firstcomposite build up pad 34 and second composite build up pad 38. Secondsupport assembly 71 is collapsible and can be inserted into space 73 ina collapsed or reduced profile and then extended and positioned againstfirst composite build up pad 34 and second composite build up pad 38. Atthe time of completion of co-curing second support assembly 71, in thisexample, can be collapsed or reduced in profile and pulled out of space73 and from edge joint 16.

The supporting, as discussed above, of the composite material inassembly of edge joint 16, permits the fabricator to maintain thecomposite material in alignment and undistorted during the assembly andthrough the desired co-curing process. With the support being providedby a collapsible structure or by a gas which can be released, thesupport can be removed from the interior of edge joint 16. In thisexample, space 73 that is provided between first composite build up pad34 and second composite build up pad 38 with second support assembly 71removed, space 73 provides the fabricator the opportunity to securebridge composite structure 72, as will be discussed, between firstcomposite build up pad 34 and second composite build up pad 38. Withbridge composite structure 72 secured and positioned along edge joint16, the fabricator can space bolts, as described herein, along bridgecomposite structure 72 as desired. The spacing of bolts along edge jointassembly 16 can provide enhanced load carrying capability with closerspacing of bolts, for example, with bolts connecting first section 18and second section 20 of wall assembly 12. This enhanced load carryingcapability is further supported with the transference of the load to thefirst and second buildup pads 34, 38, to the composite flute coremembers 26 and to first and second composite face sheets 22, 24.

Method 200 further includes a step of heating and co-curing firstcomposite face sheet 22, first composite buildup pad 34, composite flutecore member 26; second composite buildup pad 38 and second compositeface sheet 24. In this example, where a circular construction of arocket is being assembled, sections of edge joint 16 are assembled insections up to approximately twenty degrees of the circumference of therocket structure.

With the co-curing accomplished for edge joint 16, method 200 furtherincludes a step of laying up composite bridge structure 72 and postbonding composite bridge structure 72 to first and second compositebuildup pads 34, 38, as can be post bonded in position between first andsecond composite build up pads 34, 38, as seen in FIG. 11.

Method 200 further includes a step of drilling first hole 74 whichextends in first direction 76 through first composite face sheet 22,first composite buildup pad 34, composite bridge structure 72, secondcomposite buildup pad 38 and through second composite face sheet 24.Further included is a step of drilling first portion 78 of second hole80 in composite bridge structure 72 in second direction 82 transverse tofirst direction 76 placing first portion 76 in communication with firsthole 74. Drilling further includes drilling second portion 84 of secondhole 80 positioned spaced apart from first portion 76 of second hole 80across the first hole 74 and aligned with first portion 78 of secondhole 80.

With first hole 74 and second hole 80 completed method 200 furtherincludes a step of inserting barrel nut 86 into first hole 74 andinserting bolt 94 into second hole 80 and securing bolt 94 to barrel nut86.

A third example of a method for assembling a composite wall assembly 12edge joint 16 includes method 300, as set forth in FIG. 14. Thecomponents of the assembly of composite wall assembly 12 edge joint 16fabricated under method 300 that are common to previously describedcomponents for the assembling of composite wall assembly 12 edge joint16 fabricated under methods 100 and 200 are similarly numbered. As willbe appreciated herein, the assembly fabricated under the third exampleof a method or method 300, in contrast to the assembly fabricated undermethod 200, the elements of composite wall assembly 12 edge joint 16under method 300 employ a cured composite flute core member 26 inassembling edge joint 16.

In referring to FIG. 14, method 300 for assembling composite wallassembly 12 edge joint 16, includes step 302 of laying up compositefirst face sheet 22, as seen in FIG. 15. In this example, compositefirst face sheet 22 is an inboard face sheet of this assembly. Method300 further includes step 304 of laying up a first composite buildup pad34 having a first tapered section 36 onto composite first face sheet 22.Step 306 includes positioning cured composite flute core member 26 whichincludes tapered first portion 42 with first inclined surface 52 andsecond inclined surface 64. First inclined surface 52 of cured compositeflute core member 26 is positioned onto first tapered section 36 withadhesive film 45 positioned between first inclined surface 52 and firsttapered section 36. Second portion 44 of composite flute core member 26extends from tapered first portion 42 along first composite face sheet22 wherein adhesive film 45 is positioned between second portion 44 ofcomposite flute core member 26 and composite first face sheet 22. Method300 further includes step 308 laying up second composite buildup pad 38having second tapered section 40 wherein second composite buildup pad 38is positioned spaced apart from first composite buildup pad 34 having atleast a portion of second tapered section 40 overlying second inclinedsurface 64 of tapered first portion 42 of composite flute core member 26with adhesive layer 39 positioned between second tapered section 40 andsecond inclined surface 64 of tapered first portion 42 of compositeflute core member 26.

Method 300 further includes a step of positioning support structure 71between spaced apart first composite buildup pad 34 and second compositebuildup pad 38, as seen in FIG. 13. Method 300 further includes a stepof laying up a second composite face sheet 24 onto second compositebuild up pad 38 and in overlying relationship with second portion 44 ofcured composite flute core member 26 with adhesive film 39, as seen inFIG. 15, positioned between second composite face sheet 24 and secondportion 44 of composite flute core member 26.

Method 300 further includes a step of heating first composite face sheet22, first composite buildup pad 34, composite flute core member 26,second composite buildup pad 38 and second composite face sheet 24.Method 300 further includes a step of laying up composite bridgestructure 72 and post bonding composite bridge structure 72 to first andsecond composite buildup pads 34, 38.

Method 300 further includes, in this example, drilling first hole 74 infirst direction 76, as seen for example in FIG. 11, through compositefirst face sheet 22, first composite buildup pad 34, composite bridgestructure 72, second composite buildup pad 38 and second composite facesheet 24, as seen in FIG. 15. Further included is drilling first portion78, as seen for example in FIG. 11, of second hole 80 in compositebridge structure 72 in second direction 82 transverse to first direction76 placing first portion 78 in communication with first hole 74 anddrilling second portion 84 of second hole 80 positioned spaced apartfrom first portion 78 of second hole 80 across first hole 74 and alignedwith first portion 78 of second hole 80. Method 300 further includesinserting barrel nut 86 into first hole 74 and inserting bolt 94 intosecond hole 80 and securing bolt 94 to barrel nut 86.

While various embodiments have been described above, this disclosure isnot intended to be limited thereto. Variations can be made to thedisclosed embodiments that are still within the scope of the appendedclaims.

What is claimed:
 1. A method for assembling a composite wall assemblyedge joint, comprising steps of: laying up a first composite face sheet;laying up a first composite buildup pad having a first tapered sectiononto the first composite face sheet; positioning a composite flute coremember, comprising a tapered first portion comprising a first inclinedsurface and a second inclined surface wherein: the first inclinedsurface of the composite flute core member is positioned onto the firsttapered section of the first composite buildup pad; and a second portionof the composite flute core member extends from the tapered firstportion along first composite face sheet; and laying up a secondcomposite buildup pad having a second tapered section wherein the secondcomposite buildup pad is positioned spaced apart from the firstcomposite buildup pad having at least a portion of the second taperedsection of the second composite buildup pad overlying the secondinclined surface of the tapered first portion of the composite flutecore member.
 2. The method for assembling of claim 1, wherein the stepof laying up the first buildup pad further including the step of layingup of the first buildup pad to extend in a direction away from a firstend of the first composite face sheet with the first tapered sectionhaving a thickness reducing in dimension as the first composite builduppad extends in a direction away from the first end.
 3. The method forassembling for claim 2, wherein the step of positioning of the compositeflute core member further including positioning the first inclinedsurface of the composite flute core member overlying the first taperedsection of the first composite buildup pad such that the first inclinedsurface of the composite flute core member increases in distance awayfrom the first composite face sheet as the composite flute core memberextends in a direction toward the first end of the first composite sheetface.
 4. The method for assembling of claim 3, wherein the step oflaying up the second composite buildup pad having the second taperedsection including configuring the second tapered section with the secondtapered section reducing in thickness as the second composite builduppad extends in a direction away from the first end of the firstcomposite face sheet with the second inclined surface of the taperedfirst portion of the composite flute core member positioned closer tothe first composite face sheet as the second inclined surface of thecomposite flute core member extends in a direction toward the first endof the first composite face sheet.
 5. The method for assembling of claim1, further including a step of supporting an interior surface of thetapered first portion and the second portion of the composite flute coremember.
 6. The method for assembling of claim 5, wherein the step ofsupporting including a step of inserting a pressurized gas into aninterior of the composite flute core member.
 7. The method forassembling of claim 5, wherein the step of supporting including a stepof inserting a collapsible support structure into the interior of thecomposite flute core member supporting the interior surface of the firstportion and the second portion of the flute core member.
 8. The methodfor assembling of claim 1, further including a step of positioning asupport structure within space between the first composite buildup padand the second composite buildup pad.
 9. The method for assembling ofclaim 1, further including a step of laying up a second composite facesheet onto the second composite buildup pad and onto the second portionof the composite flute core member which extends from the tapered firstportion of the composite flute core member.
 10. The method forassembling of claim 9, further including a step of heating the firstcomposite face sheet, first composite buildup pad, the composite flutecore member; and the second composite buildup pad and the secondcomposite face sheet.
 11. The method for assembling of claim 10, furtherincluding a step of laying up a composite bridge structure and postbonding the composite bridge structure to the first and second compositebuildup pads.
 12. The method for assembling of claim 11, furtherincluding a step of drilling a first hole in a first direction throughthe first composite face sheet, the first composite buildup pad, thecomposite bridge structure, the second composite buildup pad and thesecond composite face sheet.
 13. The method for assembling of claim 12,further including a step of drilling a first portion of a second hole inthe composite bridge structure in a second direction transverse to thefirst direction placing the first portion in communication with thefirst hole and drilling a second portion of the second hole positionedspaced apart from the first portion of the second hole across the firsthole and aligned with the first portion of the second hole.
 14. Themethod for assembling of claim 13, further including a step of insertinga barrel nut into the first hole and inserting a bolt into the secondhole and securing the bolt to the barrel nut.
 15. A method forassembling a composite wall assembly edge joint, comprising steps of:laying up a composite first face sheet; laying up a composite firstbuildup pad having a first tapered section onto the composite first facesheet; positioning a cured composite flute core member, comprising atapered first portion comprising a first inclined surface and a secondinclined surface, wherein the first inclined surface of the curedcomposite flute core member is positioned onto the first tapered sectionof the composite buildup pad with an adhesive film positioned betweenthe first inclined surface and first tapered section; and a secondportion of the composite flute core member extends from the taperedfirst portion along first composite face sheet wherein an adhesive filmis positioned between the second portion of the composite flute coremember and the first composite face sheet; and laying up a secondcomposite buildup pad having a second tapered section wherein the secondcomposite buildup pad is positioned spaced apart from the firstcomposite buildup pad having at least a portion of the second taperedsection overlying the second inclined surface of the tapered firstportion of the composite flute core member with an adhesive layerpositioned between the second tapered section and the second inclinedsurface of the tapered first portion of the composite flute core member.16. The method for assembling of claim 15, further including a step ofpositioning a support structure between the spaced apart first compositebuildup pad and the second composite buildup pad.
 17. The method forassembling of claim 15, further including a step of laying up a secondcomposite face sheet onto the second composite build up pad and inoverlying relationship with the second portion of the cured compositeflute core member with an adhesive film positioned between the secondcomposite face sheet and the second portion of the composite flute coremember.
 18. The method for assembling of claim 17, further including astep of heating the first composite face sheet, the first compositebuildup pad, the composite flute core member, the second compositebuildup pad and the second composite face sheet.
 19. The method forassembling of claim 18, further including a step of laying up acomposite bridge structure and post bonding the composite bridgestructure to the first and second composite buildup pads.
 20. The methodfor assembling of claim 19, further including steps of: drilling a firsthole in a first direction through the first composite face sheet, thefirst composite buildup pad, the composite bridge structure, the secondcomposite buildup pad and the second composite face sheet; drilling afirst portion of a second hole in the composite bridge structure in asecond direction transverse to the first direction placing the firstportion in communication with the first hole and drilling a secondportion of the second hole positioned spaced apart from the firstportion of the second hole across the first hole and aligned with thefirst portion of the second hole; and inserting a barrel nut into thefirst hole and inserting a bolt into the second hole and securing thebolt to the barrel nut.